U.S. patent number 10,086,806 [Application Number 15/239,335] was granted by the patent office on 2018-10-02 for brake-by-wire system including coastdown mode.
This patent grant is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS LLC. The grantee listed for this patent is GM Global Technology Operations LLC. Invention is credited to Christopher C. Chappell, Paul A. Kilmurray, Brandon C. Pennala.
United States Patent |
10,086,806 |
Pennala , et al. |
October 2, 2018 |
Brake-by-wire system including coastdown mode
Abstract
A vehicle is provided. The vehicle includes a vehicle system.
The vehicle system includes a brake-by-wire portion, which also
includes a controller. The controller can cause a forced coastdown
of the vehicle. The forced coastdown includes performing analyzing
conditions of the vehicle system to determine whether the vehicle
is in a stable state and to determine an amount of energy available
to the vehicle system and automatically applying the forced
coastdown when the vehicle is not in the stable state and the
amount of energy is less than or equal to a threshold for continued
manual operation of the vehicle. The forced coastdown also includes
utilizing brake pressure to reduce a speed of the vehicle.
Inventors: |
Pennala; Brandon C. (Howell,
MI), Kilmurray; Paul A. (Wixom, MI), Chappell;
Christopher C. (Commerce Township, MI) |
Applicant: |
Name |
City |
State |
Country |
Type |
GM Global Technology Operations LLC |
Detroit |
MI |
US |
|
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS
LLC (Detroit, MI)
|
Family
ID: |
61082759 |
Appl.
No.: |
15/239,335 |
Filed: |
August 17, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180050672 A1 |
Feb 22, 2018 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60T
7/042 (20130101); B60T 7/12 (20130101); B60T
8/17 (20130101); B60T 13/662 (20130101); G07C
5/0808 (20130101); B60T 2270/402 (20130101); B60T
2270/82 (20130101); B60T 2270/403 (20130101) |
Current International
Class: |
B60T
7/12 (20060101); G07C 5/08 (20060101); B60T
8/17 (20060101); B60T 7/04 (20060101); B60T
13/66 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tran; Khoi H
Assistant Examiner: Nguyen; Robert T
Attorney, Agent or Firm: Cantor Colburn LLP
Claims
What is claimed is:
1. A method of executing a forced coastdown of a vehicle, the
method implemented by a controller of a brake-by-wire portion of a
vehicle system of the vehicle, the method comprising: analyzing
conditions of the vehicle system to determine whether the vehicle
is in a stable state and to determine an amount of energy available
to the vehicle system; and automatically applying the forced
coastdown when the vehicle is not in the stable state and the
amount of energy is less than or equal to a threshold for continued
manual operation of the vehicle, wherein the forced coastdown
comprises utilizing brake pressure to reduce a speed of the
vehicle.
2. The method of claim 1, wherein the method comprises: determining
that the vehicle system is operating on back-up power, wherein the
amount of energy is an amount of the back-up power.
3. The method of claim 1, wherein the method comprises: determining
whether a degraded state should be applied to the continued manual
operation of the vehicle.
4. The method of claim 1, wherein the method comprises: determining
an amount of energy required to execute the forced coastdown based
on a surface grade.
5. The method of claim 1, wherein the forced coastdown comprises
providing a controlled vehicle deceleration of the speed of the
vehicle based on a time based target speed.
6. The method of claim 1, wherein the stable state includes when
the vehicle is stationary.
7. The method of claim 1, wherein the forced coastdown comprises
utilizing brake pressure to reduce the speed of the vehicle to a
target profile that simulates a level ground coastdown.
8. The method of claim 1, wherein the conditions of the vehicle
system indicate circumstances of and surrounding the vehicle.
9. The method of claim 1, wherein the conditions of the vehicle
system are detected based on a plurality of inputs, the plurality
of inputs comprising a battery state of charge of a back-up power
source and wheel speeds, wherein the battery state of charge is
utilized by the vehicle system to determine the amount of energy,
and wherein the wheel speeds are utilized by the vehicle system to
determine the speed of the vehicle.
10. The method of claim 1, wherein the method comprises: engaging a
parking brake to secure the vehicle in a stationary state when the
vehicle is in the stable state.
11. A vehicle system of a vehicle, the vehicle system comprising: a
brake-by-wire portion comprising a controller configured to cause a
forced coastdown of the vehicle by causing the vehicle system to
perform: analyzing conditions of the vehicle system to determine
whether the vehicle is in a stable state and to determine an amount
of energy available to the vehicle system; and automatically
applying the forced coastdown when the vehicle is not in the stable
state and the amount of energy is less than or equal to a threshold
for continued manual operation of the vehicle, wherein the forced
coastdown comprises utilizing brake pressure to reduce a speed of
the vehicle.
12. The vehicle system of claim 11, wherein the controller is
configured to cause the vehicle system to perform: determining that
the vehicle system is operating on back-up power, wherein the
amount of energy is an amount of the back-up power.
13. The vehicle system of claim 11, wherein the controller is
configured to cause the vehicle system to perform: determining
whether a degraded state should be applied to the continued manual
operation of the vehicle.
14. The vehicle system of claim 11, wherein the controller is
configured to cause the vehicle system to perform: determining an
amount of energy required to execute the forced coastdown based on
a surface grade.
15. The vehicle system of claim 11, wherein the forced coastdown
comprises providing a controlled vehicle deceleration of the speed
of the vehicle based on a time based target speed.
16. The vehicle system of claim 11, wherein the stable state
includes when the vehicle is stationary.
17. The vehicle system of claim 11, wherein the forced coastdown
comprises utilizing brake pressure to reduce the speed of the
vehicle to a target profile that simulates a level ground
coastdown.
18. The vehicle system of claim 11, wherein the conditions of the
vehicle system indicate circumstances of and surrounding the
vehicle.
19. The vehicle system of claim 11, wherein the conditions of the
vehicle system are detected based on a plurality of inputs, the
plurality of inputs comprising a battery state of charge of a
back-up power source and wheel speeds, wherein the battery state of
charge is utilized by the vehicle system to determine the amount of
energy, and wherein the wheel speeds are utilized by the vehicle
system to determine the speed of the vehicle.
20. The vehicle system of claim 11, wherein the controller is
configured to cause the vehicle system to perform: engaging a
parking brake to secure the vehicle in a stationary state when the
vehicle is in the stable state.
Description
FIELD OF THE INVENTION
The invention disclosed herein relates to a vehicle having a
brake-by-wire system including coastdown mode.
BACKGROUND
Conventional braking systems provide direct mechanical linkages
and/or hydraulic force-transmitting-paths between an operator and
brake control units of the vehicle. Conventional braking systems
also add a significant weight penalty to the vehicle itself. Thus,
reducing or replacing the conventional braking systems is
desirable.
Current industrial trends include reducing a number of overall
mechanical components and an overall weight of the vehicle through
system-by-wire applications, also referred to as X-by-wire systems.
One such X-by-wire system is a brake-by-wire system, which may be
referred to as an electronic braking system (EBS). Present
implementations of brake-by-wire systems may not to include
electrical redundancy vs mechanical redundancy (e.g., duplication
of hardware and/or software to account for component failures),
fault tolerance (e.g., overcoming undesired events affecting
control signals, data, hardware, software or other elements of such
systems), fault monitoring (e.g., detecting undesired events), and
other security mechanisms to ensure braking.
SUMMARY OF THE INVENTION
In one exemplary embodiment, a vehicle is provided. The vehicle
comprises a vehicle system. The vehicle system comprises a
brake-by-wire portion comprising a controller. The controller is
configured to cause a forced coastdown of the vehicle by causing
the vehicle system to perform analyzing conditions of the vehicle
system to determine whether the vehicle is in a stable state and to
determine an amount of energy available to the vehicle system; and
automatically applying the forced coastdown when the vehicle is not
in the stable state and the amount of energy is less than or equal
to a threshold for continued manual operation of the vehicle,
wherein the forced coastdown comprises utilizing brake pressure to
reduce a speed of the vehicle.
In another exemplary embodiment, a method of executing a forced
coastdown of a vehicle is provided. The method is implemented by a
controller of a brake-by-wire portion of a vehicle system of the
vehicle. The method comprises analyzing conditions of the vehicle
system to determine whether the vehicle is in a stable state and to
determine an amount of energy available to the vehicle system; and
automatically applying the forced coastdown when the vehicle is not
in the stable state and the amount of energy is less than or equal
to a threshold for continued manual operation of the vehicle,
wherein the forced coastdown comprises utilizing brake pressure to
reduce a speed of the vehicle.
The above features and advantages are readily apparent from the
following detailed description when taken in connection with the
accompanying drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features, advantages and details appear, by way of example
only, in the following detailed description of embodiments, the
detailed description referring to the drawings in which:
FIG. 1 is a top schematic view of a vehicle having a brake-by-wire
system in accordance with an embodiment;
FIG. 2 is a top schematic view of a brake-by-wire system in
accordance with an embodiment;
FIG. 3 is a brake-by-wire system in accordance with another
embodiment;
FIG. 4 is a process flow of a coastdown mode of a brake-by-wire
system in accordance with another embodiment; and
FIG. 5 is a process flow of a coastdown mode of a brake-by-wire
system in accordance with another embodiment.
DESCRIPTION OF THE EMBODIMENTS
The following description is merely exemplary in nature and is not
intended to limit the present disclosure, its application or uses.
It should be understood that throughout the drawings, corresponding
reference numerals indicate like or corresponding parts and
features.
In accordance with an embodiment, FIG. 1 is a top schematic view of
a vehicle 100. As illustrated in FIG. 1, the vehicle 100 includes a
first wheel pair 105 (e.g., a wheel 105a and a wheel 105b), a first
axle 110, a second wheel pair 115 (e.g., a wheel 115a and a wheel
115b), a second axle 120, an engine 130, a transmission 135, a
driveshaft 140, a differential assembly 145, a brake-by-wire system
150, and a plurality of brake assemblies 160a-d.
The vehicle 100 may be any automobile, truck, van, sport utility
vehicle, or the like. As used herein, the term vehicle is not
limited to just an automobile, truck, van, or sport utility
vehicle, but may also include any self-propelled or towed
conveyance suitable for transporting a burden. Thus, it should be
appreciated that the brake-by-wire system 150 described herein may
be used with any type of vehicle.
The vehicle 100 may include an engine 130, such as a gasoline or
diesel fueled internal combustion engine. The engine 130 may
further be a hybrid type engine that combines an internal
combustion engine with an electric motor. The engine 130 may also
be entirely electric. The engine 130 can be coupled to a frame or
other chassis structure of the vehicle 100.
The vehicle 100 may include the first wheel pair 105 arranged
adjacent the engine 130 (and connected via a transmission, a
driveshaft, a differential assembly, etc., each of which is not
shown for simplicity). The engine 130 can also be coupled to the
second wheel pair 115 through the transmission 135, the driveshaft
140, and the differential assembly 145. The wheels 105a, 105b,
115a, 115b can be configured to receive outputs from the engine 130
individually, as pairs, or in conjunction with one another.
For example, when the engine 130 is engaged with one or both of the
first wheels (105a and 105b), the vehicle 100 may be said to
include a front-wheel drive configuration. When the engine 130 is
engaged with one or both of the second wheels (115a and 115b), the
vehicle 100 may be said to include a rear-wheel drive
configuration. When the engine 130 is simultaneously engaged with
both the first wheel pair 105 and the second wheel pair 115, the
vehicle 100 may be said to include a four-wheel or an all-wheel
drive configuration.
The transmission 135 may be configured to reduce a rotational
velocity and increase a torque output of the engine 130. In an
embodiment, a modified output can then be transmitted to the
differential assembly 145 via the driveshaft 140. The differential
assembly 145 transmits the output torque from the driveshaft 140
through a differential gear set to the second wheel pair 115 via
the second axle 120. The differential gear set is arranged within
the differential assembly 145.
The vehicle 100 includes the brake-by-wire system 150 and at least
one of the brake assemblies 160a-d. The brake-by-wire system 150
can be an exclusive-by-wire-system that enables braking torque to
the wheels (105a, 105b, 115a, and 115b). Each of the brake
assemblies 160a-d can be a device for applying braking torque to
the wheels (105a, 105b, 115a, and 115b) to slow or stop a motion of
the vehicle 100, such as by contact friction, magnetic operation,
etc.
The brake-by-wire system 150 can include one or more components,
such as electrical motors, actuators, driver interface devices,
emulators, isolators, power electronics, control electronics,
modules, drivers, and the brake assemblies 160a-d. The components
can be electronically coupled and located throughout the vehicle
100.
For example, the brake-by-wire system 150 can utilize and
distribute electrical power from power electronics, such as battery
sub-systems of the vehicle 100 or the brake-by-wire system 150 to
the components therein. Further, the brake-by-wire system 150 can
also include driver interface devices, such as a brake pedal, a
parking brake lever, an input button/dial/lever, etc. Each of the
driver interface devices can cause the direct application of
braking torque (e.g., amount of clamping force) to the wheels
(105a, 105b, 115a, and 115b), provide an electrical boost to
mechanical and/or hydraulic braking systems, and/or support braking
when there is no way to generate braking torque from the
application of the brake pedal. Thus, the brake-by-wire system 150
can forgo, supplement, assist, or include a mechanical back-up.
In an embodiment, the plurality of brake assemblies 160a-d can be
physically and/or electrically connected by electrical conductors
(e.g., wires) to the brake-by-wire system 150, and thus can be
considered included therein. Each of the plurality of brake
assemblies 160a-d can be referred to as a brake corner, a brake
assembly, a caliper/rotor assembly, etc. In general, a brake corner
can include a caliper, a rotor, an isolator, a driver, and an
actuator, where the actuator applies a clamping force from the
caliper to the rotor based on a deceleration signal received
through the isolator and the driver. Thus, each of the plurality of
brake assemblies 160a-d can be configured to selectively slow the
rotation of an associated wheel (105a, 105b, 115a, or 115b).
Each of the plurality of brake assemblies 160a-d can be configured
to respond, whether independently or in concert, to a deceleration
action from the brake-by-wire system 150. For instance, by applying
braking torque to a brake pedal, activating a parking brake,
operating an input button or lever, etc., an operator of a vehicle
causes a deceleration signal to be sent from the brake-by-wire
system 150 to the plurality of brake assemblies 160a-d.
With respect to the brake pedal, force and travel sensors can be
coupled to the brake pedal to detect elements of a clamping force
and/or calculate an amount of the clamping force. The clamping
force can be translated by the brake-by-wire system 150 into the
deceleration signal. A sensor is any converter that measures
physical quantities and converts these physical quantities into a
signal (e.g., raw sensor data, such as voltage in analog form; also
referred to as analog sensor data). Thus, a sensor can be any
device configured to detect status/condition information of
mechanical machinery of the vehicle 100 of FIG. 1 and/or control
electronics of the vehicle 100 of FIG. 1 and produce the analog
sensor data. Examples of sensors include, but are not limited to,
strain gauges that measure the physical stress or force applied
(e.g., fiber optic gauges, foil gauges, capacitive gauges, etc.);
travel sensors that measure movement (e.g., accelerometers,
gyroscopes, etc.); and temperature sensors that measure the
temperature characteristics and/or the physical change in
temperature (e.g., fiber optic temperature sensors, heat meters,
infrared thermometers, liquid crystal thermometers, resistance
thermometers, temperature strips, thermistors, thermocouples,
etc.).
With respect to the parking brake, a travel sensor can be coupled
to the parking brake to detect an on-position that is translated by
the brake-by-wire system 150, which in this case can indicate a
predetermined clamping force that provides a full stop. The input
button/dial/lever can also operate to receive an input from the
operator to enable the brake-by-wire system 150 to generate, as the
deceleration signal, a predetermined and/or variable clamping
force. The deceleration signal causes the plurality of brake
assemblies 160a-d, whether individually or in concert, to apply a
braking torque on corresponding wheels that result in wheel
rotational deceleration.
The brake-by-wire system 150 will now be described according to an
embodiment and with reference to FIG. 2. As illustrated, the
brake-by-wire system 150 can be embodied as a system 200. The
system 200 can include a controller 205, an actuator 210, a driver
interface device 215, an isolator 220, a driver 225, power
electronics 230, a module 235, a first brake 241, a second brake
242, a third brake 243, and a fourth brake 244. The components of
the system 200 can be electronically coupled and located throughout
the vehicle 100 of FIG. 1, along with being configured to
communicate/interact with each other. While single items are
illustrated by FIG. 2 for each component of the system 200, these
representations are not intended to be limiting and thus, the each
component may represent a plurality of that component. It should be
appreciated that the system 200 can include other components used
in the operation of the vehicle 100 of FIG. 1, that the system 200
may also include fewer modules, that the components can be embodied
in separate arrangements in a distributed manner, and that the
components can be an integrated control scheme.
The system 200 can be referred to as a control system of the
brake-by-wire system 150. The system 200 can, via input/output
(I/O) interfaces, receive inputs, such as operator input from the
driver interface device 215 and environmental inputs from sensors
of the vehicle 100 of FIG. 1. The I/O interfaces can include any
physical and/or virtual mechanisms utilized by the system 200 to
communicate between components internal and/or external to the
system 200 (e.g., the I/O interfaces can be configured to receive
or send signals or data within or for the system 200). The inputs
are processed by the controller 205.
The controller 205 can generate commands and/or currents to drive
the actuator 210. In general, the controller 205 receives a signal
from the driver interface device 215, processes the signal, and
generates a command to the driver 225 based on the processed signal
(e.g., the driver in turn communicates with the actuator 210, which
operates one or more of the brakes 241-244). In another embodiment,
the sensors detect travel/force/etc. imparted by an operator of the
vehicle 100 of FIG. 1 when commanding deceleration. The
travel/force/etc. signals are used to determine an amount of
deceleration (e.g., a clamping force). The driver 225 communicates
the amount of deceleration with the driver interface device 215,
which is further communicated to the actuators 210 and actually
applied to the brakes 241-244 at the wheels.
The controller 205 includes any processing hardware, software, or
combination of hardware and software utilized by the system 200
that carries out computer readable program instructions by
performing arithmetical, logical, and/or input/output operations.
The controller 205 can include a memory (e.g., a tangible device)
configured to store software and/or computer readable program
instructions. Examples of the controller 205 include, but are not
limited to, an arithmetic logic unit, which performs arithmetic and
logical operations; a control unit, which extracts, decodes, and
executes instructions from a memory; and an array unit, which
utilizes multiple parallel computing elements. Other examples of
the controller include an electronic control
module/unit/controller, electronic parking brake module, and an
application specific integrated circuit. In an embodiment, the
system 200 can include two or more controllers 205 to meet
requirements of power assist failures, such that if a first
controller fails then a second or subsequent controller 205
continues operation.
The actuator 210 can be any type of motor that converts energy into
motion, thereby controlling the movement of a mechanism, such as
the brakes 241-244, based on received signals. Thus, the actuator
210 can be a direct current motor configured to generate
electro-hydraulic braking torque to the corner (e.g., the brake
corner, the brake assembly, the caliper/rotor assembly, etc.). The
driver interface device 215 can be any combination of hardware and
software that enables a component of the system 200 to behave like
a component not included in, or replaced by, the system 200. For
example, the driver interface device 215 can be a pedal emulator
that behaves like a mechanical pedal of a hydraulic braking system.
The isolator 220 can be device that transmits signals (e.g.,
microwave or radio frequency power) in one direction only and
shields components on an input side, from the effects of conditions
on an output side.
The driver 225 can be a device that transmits signals based on
commands of the controller 205 to the actuator 210. The driver 225,
like the controller 205, can include any processing hardware,
software, or combination of hardware and software utilized by the
system 200 that carries out computer readable program instructions
by performing arithmetical, logical, and/or input/output
operations. The driver 225 can include a memory (e.g., a tangible
device) configured to store software and/or computer readable
program instructions.
The power electronics 230 can control and manage electrical power
throughout the system 200 and vehicle 100 of FIG. 1. The power
electronics 230 can include, but are not limited to, batteries,
fuses, semi-conductor based devices that are able to switch
quantities of power, rectification devices, AC-to-DC conversion
devices, and DC-to-AC conversion devices. The power electronics 230
can include or be in communication with first and secondary power
sources to operate the system 200. For example, the first power
source can be a primary 12 volt system that provides all power to
run engine 130 of FIG. 1 etc., and the secondary power source can
be a battery that powers the vehicle 100 of FIG. 1 when the primary
power source fails.
The module 235 can include any processing hardware, software, or
combination of hardware and software utilized by the system 200 to
receive and respond to signals within the system. The module 235
can be embodied within the controller 205 as hardware and/or
computer readable program instructions stored on a memory of the
controller. Thus, in an embodiment, the controller 205 can be
referred to as an electronic brake controller that includes a
plurality of modules 235 (e.g., sub-components), such as an
electronic parking brake module and a brake assist module.
In an embodiment, the electronic parking brake module transmits a
signal to a plurality of actuators 210 causing brake calipers of
the brakes 241-244 to clamp rotors with the desired amount of
clamping force. This transmitted signal can include a clamping
force, which in this case can indicate a predetermined clamping
force that provides a full stop.
The brake assist module can determine parameters associated with
deceleration actions and determine if assistance should be provided
to aid braking and how much assistance is to be applied. The brake
assist module can send a signal to an engine control module to
request that an engine reduce the power output, which will aid in
decelerating the vehicle 100.
The brake assist module further monitors the operation of the
vehicle 100 of FIG. 1, such as via the brake apply sensors (e.g.,
brake pedal travel and brake pedal force) and the wheel speed
sensors. In the event that the brake assist module determines, such
as via sensors that indicate the vehicle 100 of FIG. 1, the
brake-by-wire system 150, or the system 200 of FIG. 2 is not
operating at a desired performance level, a signal may be
transmitted to the electronic parking brake module.
The brakes 241-244 are devices for slowing or stopping motion of
the vehicle 100 of FIG. 1. Each of the brakes 241-244 can be
referred to as a brake assembly, brake corner, brake assembly, a
caliper/rotor assembly, etc. Each of the brakes 241-244 can be
configured to respond, whether directly or in concert, to a
deceleration action from the emulator 215 and/or controller
205.
In an embodiment, an application of the brake-by-wire system 150
can be adjusted based on the operational characteristics of the
vehicle 100. For example, when the vehicle 100 of FIG. 1 is
traveling at a slower speed the controller 205 can operate the
actuator 210 to apply an increased amount of clamping force to a
corresponding one of the brakes 241-244 at a slower rate than at a
faster rate required when the vehicle 100 is travelling at a higher
speed. Further, the controller 205 can monitor the wheels,
determine if there is any wheel lockup, and adjust the amount of
clamping force on any one of the brakes 241-244 to alleviate or
prevent the lockup from occurring.
Turning now to FIG. 3, the system 200 of FIG. 2 will now be
described with reference to a system 300 according to an
embodiment. As illustrated, the system 300 can include a controller
305, an actuator 310, an emulator 315, and power electronics 330.
The items illustrated by FIG. 3 are representations and are not
intended to be limiting. Thus, each component may represent a
plurality of that component and/or each plurality may represent a
singular iteration thereof. It should also be appreciated that the
system 300 can include other components, that the system 300 can
include fewer components, that the components can be embodied in
separate arrangements in a distributed manner, and that the
components can be embodied in an integrated control scheme. For
example, the actuator 310 is illustrated as a plurality of
actuators 310 notated by the actuator 310-LF, the actuator 310-RR,
the actuator 310-LR, and the actuator 310-RF, where each actuator
of the plurality is aligned with and controls braking at a
corresponding wheel (of a vehicle 100 of FIG. 1).
The components of the system 300 can be electronically coupled and
located throughout the vehicle 100 of FIG. 1, along with being
configured to communicate/interact with each other. As shown in
FIG. 3, signals and power wirings are identified by various arrows
and lines. The signals/communications between the controller 305
and the emulator 315 are indicated by the signal A and between the
controller 305 and the actuators 310 are indicated by the signals
B-LF, B-RR, B-LR, and B-RF. The power wirings C-CT, C-LF, C-RR,
C-LR, and C-RF represent the coupling of the power electronics 330
and other components.
In general, the system 300 provides a braking scheme through a
robust implementation of multiple components and/or algorithms that
receive inputs from the emulator 315. The emulator 315 can be an
electro-mechanical device that mimics a mechanical pedal of a
hydraulic braking system (e.g., the emulator 315 can include a
pedal assembly). The emulator 315 outputs at least one braking
signal (e.g., signal A) to the controller 305.
The controller 305 can include any processing hardware, software,
or combination of hardware and software utilized by the system 300
that implements architectures to achieve an operative level for the
system 300. Note the controller 305 can be integrated into other
controllers (e.g., such as the actuators 310 of the system 300), to
reduce costs of additional hardware and/or software. The controller
305 can receive a plurality of inputs, which include inputs from
the emulator 305. Further, the plurality of inputs can include
engine revolutions per minute, vehicle speed, ambient temperature
(e.g., in and/or outside of the vehicle), wheel speeds, inertial
measurements, etc. The plurality of inputs can be used by the
controller 305 to generate commands and/or currents that drive the
actuators 310. The commands and/or currents can be responsive to
one or more of the plurality of inputs. The commands and/or
currents are, in turn, braking commands by the controller 305 to
the actuators 310 based on the operation of the emulator 315.
By applying pressure to a brake pedal of the pedal assembly of the
emulator 315, an operator causes signal A to be sent to the
controller 305. The controller 305 can process an amount of force
and a distance moved to detect that a brake signal is intended by
the operator. For example, to detect a brake signal, the electric
control unit 315 can compare the amount of force and/or the
distance moved to a threshold or slope that may be stored in a
look-up table, for instance, in the memory of the controller. If
the brake signal is detected, the controller 305 can generate at
least one braking command to the actuators 310. Each braking
command, in general, can correspond to a particular actuator
310.
Example operations of the system 300 will now be described with
respect to FIGS. 4 and 5. FIG. 4 is a process flow 400 of a
coastdown mode of a brake-by-wire mechanism in accordance with an
embodiment. The coast down mode is an operating scenario of the
system 300 to automatically slow, stop, and secure the vehicle 100
operating on a depleting backup power source, in the event that an
operator fails to manually slow, stop, and secure the vehicle 100.
In this way, if the operator ignores failure notifications and does
not stop the vehicle 100, the system 300 automatically uses brake
pressure to control vehicle speed to a target profile designed to
simulate a coast down on level ground. In an example, the coast
down mode can be active primarily on downhill grades, where the
vehicle is able to sustain motion for a long period of time even
after propulsion capability has been disabled.
The process flow 400 begins at start circle 405 once the system 300
has previously determined that the system 300 is operating on
back-up power. The controller 305 of the system 300 can make this
determination based on communication with the power electronics
330. From the start circle 405, the process flow 400 proceeds to
block 410. At block 410, the system 300 executes a system check.
The system check enables the system 300 to retrieve and analyze
system conditions. The controller 305 of the system 300 can perform
the system check.
The system conditions include circumstances of and surrounding the
vehicle 100. The system conditions can be detected based on the
plurality of inputs (which are also described above), such as
battery state of charge, battery voltage, battery capacity, wheel
idle, wheel/vehicle speed, system component on/off, engine
revolutions per minute, ambient temperature, inertial measurements,
etc. The system conditions can be analyzed via comparisons against
thresholds.
For example, block 410 includes decision blocks 415 and 420. At
decision block 415, the system 300 determines whether the vehicle
100 is in a stable state. The stable state, in general, can be when
the vehicle 100 is stationary or near stationary. If the vehicle
100 is determined to not be in the stable state (e.g., the system
conditions do not meet or are outside of idle thresholds), then the
process flow 400 proceeds to decision block 420 (as indicated by
the `N` arrow).
Further, at decision block 420, the system 300 determines whether
the vehicle 100 is storing sufficient power for continued manual
vehicle operation. If the system 300 has sufficient power for
continued manual vehicle operation (e.g., the system conditions
meet or are greater than power thresholds), then the system 300 can
message an operator to manually place the vehicle in a stable state
and the process flow 400 can loop back to decision block 415 (as
indicated by the `Y` arrow). In this way, the thresholds utilized
during the system check can be predefined parameters that indicate
the stable state and/or sufficient power for continued manual
vehicle operation.
Returning to decision block 415, if the vehicle 100 is determined
to be in the stable state (e.g., the system conditions meet or are
within idle thresholds), then the process flow 400 proceeds to
block 425 (as indicated by the `Y` arrow). At block 425, the brake
is applied. The brake can be the parking brake. With the parking
brake engaged, the vehicle 100 is held in a stable/stationary
state. From block 425, the process flow 400 proceeds to end circle
430, where the process flow 400 concludes.
Returning to decision block 420, if the system 300 does not have
sufficient power for continued manual vehicle operation (e.g., the
system conditions do not meet or are below power thresholds), then
the process flow proceeds to block 435 (as indicated by the `N`
arrow). At block 435, the system 300 can automatically activate a
forced coastdown of the vehicle 100 (e.g., use brake pressure to
control vehicle speed to a stable state). In an embodiment, the
system 300 automatically applies the forced coastdown when the
vehicle is not in the stable state and the amount of energy is less
than or equal to a threshold for continued manual vehicle
operation. Next, the process flow 400 proceeds to block 425, where
the brake is applied. With the parking brake engaged, the vehicle
100 is held in a stable/stationary state. From block 425, the
process flow 400 proceeds to end circle 430, where the process flow
400 concludes.
FIG. 5 illustrates another process flow 500 of a coastdown mode of
a brake-by-wire mechanism in accordance with another embodiment. In
this embodiment, the coastdown mode includes a coastdown curve that
intrusively brakes/stops the vehicle 100 of FIG. 1 as if the
vehicle 100 of FIG. 1 is on level ground. For instance, the
coastdown curve implemented by the process flow 500 prevents
vehicle runaway on a grade by detecting when the system 300 of FIG.
3 is operating on depleting power sources for an extended period of
time and forcing an automatic coastdown to a stable state. This
automatic coastdown by the process flow 500 accounts for any long
downhill grade and an operator's failure to stop the vehicle,
despite a propulsion system of the vehicle being disabled. In
addition, the coastdown mode can enforce a brake-by-wire degraded
state strategy (ensuring stable operation), while minimizing
unnatural feel to the driver by dynamically tuning the coastdown
curve.
The process flow 500 begins at start circle 505 and proceeds to
decision block 510. At decision block 510, the system 300
determined whether the system 300 is operating on back-up power.
The controller 305 of the system 300 can make this determination
based on communication with the power electronics 330. If the
system is not operating on back-up power, the process flow 500 can
loop back to the start circle 505 and continue monitoring for when
the system is on back-up power (as indicated by the `N` arrow). If
the system is operating on back-up power, the process flow 500
proceeds to block 515.
At block 515, the system 300 can message an operator. The
controller 305 of the system 300 can control sending and displaying
of the message (e.g., failure indications and warnings). For
instance, the system 300 can activate a driver indication that
informs the operator operating on back-up power. The driver
indication can be a single Boolean light, where `on` indicates
utilization of the back-up power source and `off` indicates
utilization of the primary power source. The driver indication can
be generated through a driver information center of the vehicle
100. The driver information center can be a dashboard console that
includes lights and/or a display for providing messages to the
operator, such as an alpha numeric message and/or a symbol
indicating `on` and `off` conditions of the back-up power
source.
Next, the process flow 500 proceeds to decision block 520, where
the system 300 determines whether the vehicle 100 is in a stable
state. If the vehicle 100 is determined to be in the stable state
(e.g., the system conditions meet or are within the idle
thresholds), then the process flow 500 proceeds to block 525 (as
indicated by the `Y` arrow). At block 525, the brake is applied.
The brake can be the parking brake. With the parking brake engaged,
the vehicle 100 is held in a stable/stationary state. From block
525, the process flow 500 proceeds to end circle 530 and concludes.
If the vehicle is determined to not be in the stable state (e.g.,
the system conditions do not meet or are outside of the idle
thresholds), then the process flow 500 proceeds to block 540 (as
indicated by the `N` arrow).
At block 540, the system 300 of FIG. 3 estimates an amount of
energy required to execute a forced coastdown. The controller 305
of the system 300 of FIG. 3 can make this determination based on
communication with the power electronics 330 of FIG. 3 and based on
receiving a plurality of inputs. In general, to estimate the amount
of energy, the system 300 of FIG. 3 determines how much power will
be needed for an autonomously controlled deceleration and
immobilization in the event of impending system unavailability. The
system 300 of FIG. 3 can determine a grade of the ground or surface
supporting the vehicle 100 of FIG. 1. That is, the system 300 of
FIG. 3 can determine whether the grade of the surface supporting
the vehicle 100 of FIG. 1 is greater than zero (e.g., a current
surface grade) and/or determine whether the grade is dynamically
changing over time (e.g., a grade delta). The current surface grade
and/or the grade delta can be included in the estimating of the
amount of energy needed for the autonomously controlled
deceleration and immobilization of the vehicle 100 of FIG. 1. The
process flow 500 then proceeds to block 545.
At decision block 545, the system 300 of FIG. 3 determines whether
the vehicle 100 of FIG. 1 is storing sufficient power for continued
manual vehicle operation. In an embodiment, the controller 305 of
the system 300 of FIG. 3 determines whether a capacity of a back-up
power source is greater than the estimated coastdown energy from
block 540. Further, the controller 305 of the system 300 of FIG. 3
can also determines whether the capacity of the back-up power
source is greater than the estimated coastdown energy from block
540 and an engineering margin. The engineering margin can be a
predetermined amount of energy that is added to the estimated
coastdown to assure that there will be enough to power the vehicle
100 of FIG. 1 during a forced coastdown during any system
conditions. If the system 300 of FIG. 3 has sufficient power for
continued manual vehicle operation (e.g., the system conditions
meet or are greater than power thresholds), the process flow 500
proceeds to decision block 555 (as indicated by the `Y` arrow).
At decision block 555, the system 300 of FIG. 3 determines whether
a degraded state should be applied to the continued manual vehicle
operation. A degraded state is operation mode that restricts
certain functions of the vehicle 100 of FIG. 1, such as by limiting
the propulsion system. Execution of the degraded state and
transitions thereof can be defined by functional requirements of
the vehicle, such as those set by a standards organization. For
example, when the vehicle has switched to the back-up power source
and the energy of that back-up power source is nearing a critical
level, a degraded state can prevent the vehicle from accelerating
and/or limit vehicle speed while allowing manual braking and
steering. In this way, the degraded state can ensure vehicle
operation by automatically eliminating any increases in vehicle
kinetic energy and providing manual operation of the brakes.
As shown in FIG. 5, for example, the system 300 of FIG. 3 can
determine whether one of three state options, two of which include
a variation on a degraded state, should be applied to the continued
manual vehicle operation. The three state options include a normal
operational state, a primary degraded state, and a critical
degraded state. The normal operational state is a vehicle mode
where the operator has complete manual control of the vehicle. The
primary degraded state is a vehicle mode where the operator has
manual control of the vehicle 100 of FIG. 1 with limited propulsion
capabilities. The critical degraded state is a vehicle mode where
the operator has complete steering control and braking control
(whether normal or degraded) of the vehicle 100 of FIG. 1 with no
propulsion capabilities. The system 300 of FIG. 3 can determine
which of three state options based on the how much of the stored
back-up power is available for continued manual vehicle
operation.
For instance, the controller 305 of the system 300 of FIG. 3 can
determine if the capacity of the back-up power source is greater
than, by a first percentage or a second percentage, the estimated
coastdown energy from block 540 and the engineering margin. Note
that the first percentage is greater than the second
percentage.
If the capacity of the back-up power source is greater than the
first percentage, then there is sufficient power for the normal
operational state. If there is sufficient power for the normal
operational state, the process flow 500 proceeds to block 563 (as
indicated by the `1` arrow). The sufficient power in this case is
enough total back-up power to energize all vehicle systems while
the operator manually slows, stops, and secures the vehicle 100 of
FIG. 1. At block 563, the normal operational state is applied to
the vehicle and warning messages are issued to the operator (e.g.,
through the driver information center). From block 563, the process
flow 500 proceeds to block 520.
If the capacity of the back-up power source is greater than the
second percentage but less than or equal to the first percentage,
then there is sufficient power for the primary degraded state. If
the is sufficient power for the primary degraded state, the process
flow 500 proceeds to block 565 (as indicated by the `2` arrow). The
sufficient power in this case is enough total back-up power to
energize manual control of the vehicle 100 of FIG. 1 with limited
propulsion capabilities. At block 565, the primary degraded state
is applied to the vehicle and corresponding messages are issued to
the operator (e.g., through the driver information center). From
block 565, the process flow 500 proceeds to block 520.
If the capacity of the back-up power source is greater than the
first percentage but less than or equal to the second percentage,
then there is sufficient power for the critical degraded state. If
there is sufficient power for the critical degraded state, the
process flow 500 proceeds to block 567 (as indicated by the `3`
arrow). The sufficient power in this case is enough total back-up
power to energize manual control of the vehicle 100 of FIG. 1 with
no propulsion capabilities. At block 567, the critical degraded
state is applied to the vehicle and corresponding messages are
issued to the operator (e.g., through the driver information
center). From block 567, the process flow 500 proceeds to block
520.
Returning to decision block 545, if the system 300 of FIG. 3 does
not have sufficient power for continued manual vehicle operation
(e.g., the system conditions do not meet or are below power
thresholds), then the process flow proceeds to block 570 (as
indicated by the `N` arrow). That is, if the system 300 of FIG. 3
is running on back-up power and there is not enough back-up power
to continue running the system 300, then the capacity of the
back-up power source will be less than the estimated coastdown
energy from block 540. In turn, the system should perform a forced
coastdown.
At block 570, the system 300 can automatically activate the forced
coastdown of the vehicle 100 (e.g., use brake pressure to control
vehicle speed to a stable state). The forced coastdown is applied
to the vehicle based on the operation of decision block 575, block
580, and 585. At block 575, where the system 300 determines whether
the vehicle 100 is in a stable state. If the vehicle is determined
to not be in the stable state (e.g., the system conditions do not
meet or are outside of the idle thresholds), then the process flow
500 proceeds to block 580 (as indicated by the `N` arrow). At block
580, the system 300 of FIG. 3 determines a time based target speed.
The time based target speed is a dynamic value calculated by the
system 300 of FIG. 3 that identifies a desired vehicle speed with
respect to time. From block 580, the process flow 500 proceeds to
block 585, where the system executes a closed loop speed control
based on the time based target speed (i.e., vehicle speed is
controlled using brake pressure), thereby providing a controlled
vehicle deceleration. This controlled vehicle deceleration when on
a downhill grade can have a profile similar to a normal lift
throttle coastdown on level ground.
The process flow 500 returns to block 575, where the system 300 of
FIG. 3 again determines whether the vehicle 100 is in a stable
state. If the vehicle is determined to not be in the stable state,
then the process flow 500 loops through blocks 580 and 585. In this
way, the system 300 of FIG. 3 can account for worse case
environmental condition combined with lack of operator response to
failure indications. A worse case environmental condition is a very
long grade, which requires the vehicle 100 to be stopped and
secured on an incline.
If the vehicle 100 of FIG. 1 is determined to be in the stable
state (e.g., the system conditions meet or are within the idle
thresholds), then the process flow 500 proceeds to block 525 (as
indicated by the `Y` arrow). At block 525, a brake (such as a
parking brake, i.e., mechanically latching) is applied. From block
525, the process flow 500 proceeds to end circle 530, where the
process flow 500 concludes.
Embodiments herein provide advantages in lowering the amount of
effort required to stop a vehicle. Further advantages and technical
benefits include providing a controlled vehicle deceleration on a
downhill grade, with a profile similar to a lift throttle coastdown
on level ground. Advantages and technical benefits also include
ensuring proper execution of degraded state transitions as defined
by functional requirements and ensuring vehicle operation by
automatically eliminating vehicle kinetic energy while service
brakes are still available when worse case environmental conditions
are combined with lack of operator response to failure
indications.
Aspects of embodiments herein are described with reference to
flowchart illustrations and/or block diagrams of methods, apparatus
(systems), and computer program products according to embodiments.
It will be understood that each block of the flowchart
illustrations and/or block diagrams, and combinations of blocks in
the flowchart illustrations and/or block diagrams, can be
implemented by computer readable program instructions.
These computer readable program instructions may be provided to a
processor of a general purpose computer, special purpose computer,
or other programmable data processing apparatus to produce a
machine, such that the instructions, which execute via the
processor of the computer or other programmable data processing
apparatus, create means for implementing the operations/acts
specified in the flowchart and/or block diagram block or blocks.
These computer readable program instructions may also be stored in
a computer readable storage medium that can direct a computer, a
programmable data processing apparatus, and/or other devices to
operate in a particular manner, such that the computer readable
storage medium having instructions stored therein comprises an
article of manufacture including instructions which implement
aspects of the operation/act specified in the flowchart and/or
block diagram block or blocks.
The computer readable program instructions may also be loaded onto
a computer, other programmable data processing apparatus, or other
device to cause a series of operational steps to be performed on
the computer, other programmable apparatus or other device to
produce a computer implemented process, such that the instructions
which execute on the computer, other programmable apparatus, or
other device implement the operations/acts specified in the
flowchart and/or block diagram block or blocks.
The flowchart and block diagrams in the FIGS. illustrate the
architecture, operability, and operation of possible
implementations of systems, methods, and computer program products
according to various embodiments. In this regard, each block in the
flowchart or block diagrams may represent a module, segment, or
portion of instructions, which comprises one or more executable
instructions for implementing the specified logical operation(s).
In some alternative implementations, the operations noted in the
block may occur out of the order noted in the FIGS. For example,
two blocks shown in succession may, in fact, be executed
substantially concurrently, or the blocks may sometimes be executed
in the reverse order, depending upon the operability involved. It
will also be noted that each block of the block diagrams and/or
flowchart illustration, and combinations of blocks in the block
diagrams and/or flowchart illustration, can be implemented by
special purpose hardware-based systems that perform the specified
operations or acts or carry out combinations of special purpose
hardware and computer instructions.
The flow diagrams depicted herein are just one example. There may
be many variations to this diagram or the steps (or operations)
described therein without departing from the spirit of the
disclosed. For instance, the steps may be performed in a differing
order or steps may be added, deleted or modified. All of these
variations are considered a part of the claims.
The descriptions of the various embodiments have been presented for
purposes of illustration, but are not intended to be exhaustive or
limited to the embodiments disclosed. Many modifications and
variations will be apparent to those of ordinary skill in the art
without departing from the scope and spirit of the described
embodiments. The terminology used herein was chosen to best explain
the principles of the embodiments, the practical application or
technical improvement over technologies found in the marketplace,
or to enable others of ordinary skill in the art to understand the
embodiments disclosed herein.
The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting. As
used herein, the singular forms "a", "an" and "the" are intended to
include the plural forms as well, unless the context clearly
indicates otherwise. It will be further understood that the terms
"comprises" and/or "comprising," when used in this specification,
specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one more other features, integers, steps,
operations, element components, and/or groups thereof.
While the embodiments have been described, it will be understood by
those skilled in the art that various changes may be made and
equivalents may be substituted for elements thereof without
departing from the scope of the embodiments. In addition, many
modifications may be made to adapt a particular situation or
material to the teachings of the embodiments without departing from
the essential scope thereof. Therefore, it is intended that the
disclosure not be limited to the particular embodiments disclosed,
but that the disclosure will include all embodiments falling within
the scope of the application.
* * * * *